1. Field of the Invention
This invention relates to gaseous fuel injectors for propulsion systems and more particularly to such an injector which utilizes an electromagnetic solenoid with a flat armature which forms a valve for the injector.
2. Description of the Related Art
Gaseous fuel injection systems are commonly used in supplying fuel to engines. Such systems generally utilize a spherical ball type valve which is attached to a pintle which moves in the central portion of the solenoid. A typical such prior art fuel injector is described in U.S. Pat. No. 5,775,599 issued Jul. 7, 1998 to Smith et al. and assigned to Impco Technologies Inc., the assignee of the present application. For such systems to operate effectively, the fuel must provide enough lubrication to prevent a seizure of the plunger during its operation. With liquid fuel such lubrication is readily provided but with gaseous fuel, traces of compressor oil must be relied on. With the demand to increase the purity of gaseous fuel, compressors which do not use oil as a lubricant are now being extensively used, eliminating the entry of this lubricant into the fuel. The elimination of the lubricant, however, has resulted in the deterioration of the performance of typical prior art gaseous injectors.
To solve this problem, a gaseous fuel injector having a flat solenoid armature which seats directly on a seat member to form the fuel valve has been developed. This device is described in U.S. Pat. No. 5,348,233 issued Sep. 20, 1994 to Roman Press, et al., said Roman Press being the inventor of the present invention. This prior invention, while solving the problem of wear on the valve mechanism, has the shortcoming of having a discharge nozzle which is not integrated with the injector and thus is not readily amenable to mass production. Further, the device of this prior art invention is adapted for fuel delivery to its central portion, not from the top, as in the present invention. In addition, the device of this prior invention is not designed for installation between a fuel rail and an injector port in a manner similar to a gasoline injector, as is the device of the present invention.